Rio Lagartos Research Articles

Stochastic modeling of eastern oyster (Crassostrea virginica) production in a Mexican tropical coastal lagoon using alternative stocking density management schemes

A stochastic model was developed to analyze Crassostrea virginica production when cultivated at three stocking densities, defined as the area occupation (50, 75, and 100%) in Nestier-type trays, using juvenile oysters with an initial size (height) of 29.40 ± 0.18 mm. A 25-week grow-out was first conducted in the Rio Lagartos lagoon, showing that final oyster size was inversely related to density (P < 0.05), ranging from 61.87 mm (100% density) to 68.00 mm (50% density). At the same time, mortality was negligible (lower than 1.0%). The environmental conditions in the lagoon were stable, and the oyster growth rate positively correlated with water temperature and pH. Low pH was associated with slow oyster growth, possibly as an adverse effect of acidic conditions on the oyster shell formation. The model indicated that, for an initial 100,000 oyster population, the maximum production (oyster dozens) is obtained after 20 weeks (8310 at 50% density) and 25 weeks (8250 at 75%, and 6670 at 100% density). There was a 100% probability of oysters reaching a minimum commercial size (MCS) of 60.00 mm when using the 50 and 75% densities and 80.6% when using 100%. The model estimated that, for the maximum density, extending the grow-out up to 32 weeks would allow reaching MCS with 100% probability, although this should be experimentally confirmed. The random variability of oyster production in 50 and 75% densities was minimal, while at 100% density, it was extremely high. A sensitivity analysis indicated that for 50 and 75% densities, the main stochastic elements influencing production, are related to oyster mortality, while at 100% density, they are related to oyster growth.

Genetic identification of Penaeus monodon from incipient invasions in the Yucatán Peninsula, south-southeast Gulf of Mexico

In the western Atlantic, the presence of the invasive tiger shrimp Penaeus monodon has been recorded since 1987. Established and incipient populations are reported from North Carolina, USA, to Sergipe, Brazil. In the Yucatán Peninsula, in the south-southeast Gulf of Mexico, the first sightings of P. monodon were reported in 2014. To date, the sparse records suggest an ongoing incipient invasion, providing a time-critical opportunity for early biological assessment. In the present study, two wild adults of P. monodon are reported for Rio Lagartos Lagoon, Yucatán, situated in the innermost part of the southeast Gulf of Mexico, close to the Caribbean Sea. Penaeus monodon identification was initially assessed based on macroscopic morphological features. Molecular analyses were used to corroborate morphological identification. A BLAST search was conducted by comparing partial sequences (510 bp) of the mtDNA control region (CR) of tiger shrimps from Yucatán (used as queries) with sequences deposited in the GenBank database. A Maximum Likelihood phylogenetic tree, generated from BLAST top hits (E-value cutoff = 0), revealed that sequences from Yucatán were most closely related to native sequences submitted from Indonesia. This accurate species identification has implications since this invasive shrimp threatens native biodiversity. The probable regional routes of the spread of P. monodon to the south-southeast Gulf of Mexico are discussed.

Microsatellite Loci of the Atlantic Horseshoe Crab (Limulus polyphemus) Reveal Inter-Localities Genetic Diversity in the Coastal Waters of the Eastern and Northern Yucatan Peninsula.

The American horseshoe crab (Limulus polyphemus) is an economically and ecologically important species, which is currently categorized as endangered in Mexico. L. polyphemus, one of four extant horseshoe crab species that constitute the class Merostomata, is distributed along the Atlantic coastline of the USA from Alabama to Maine and has another population on the coastline of Campeche, Yucatan, and Quintana Roo in the Yucatan Peninsula, Mexico. In the present study, we evaluated the genetic diversity and genetic structure of four separated localities along the coast of the Yucatan peninsula (Champoton, CH; Isla Arena, IA; Rio Lagartos, RL; and Holbox Island, HI), using nine microsatellite-type molecular markers for this species. The aim of this study is to obtain a baseline of the current level of genetic diversity, which would allow the monitoring of important changes over time. Multilocus analyses revealed moderate levels of genetic diversity (He, 0.5230 to 0.6389) and genetic structure within the whole study area (FST 0.025). The population from RL showed limited gene flows, differing significantly from the other sampling sites. The genetic information obtained in this study can support the implementation of management and conservation programs for this species in Mexico.

Linking phenotypic to genotypic metacestodes from Octopus maya of the Yucatan Peninsula.

Octopus maya is an endemic species of the Yucatan Peninsula. This species sustains the octopus’ fishery in the region and is the only cephalopod cultured in Mexico. It is known that O. maya harbor a large richness and abundance of metacestodes that have been tentatively identified by light microscopy alone. Since the larval stages of some orders of marine cestodes lack the taxonomic characteristics shown by the adult stages and on which cestode taxonomy is based, identification down to the species level is often unattainable. Hence, the goal of this study was to characterize the parasites, for the first time, at morphological and molecular levels. A total of 60 octopuses were collected from September to December 2017 from four fishery landing ports in Yucatán: Sisal, Progreso, Dzilam de Bravo, and Rio Lagartos (15 hosts per locality). Morphology of metacestodes was characterized by light and Scanning Electron Microscopy (SEM), while the genes 18S and 28S rDNA were sequenced for molecular characterization. Based on phenotypic characters and molecular data, seven taxa of metacestodes were identified, four of them belonging of order Trypanorhyncha: Eutetrarhynchus sp., Kotorella pronosoma, Nybelinia sp., Prochristianella sp. 1; and the three remaining taxa belonging to the order Onchoproteocephalidea: Acanthobothrium sp., Phoreiobothrium sp., and Prosobothrium sp. This work provides, for the first time, molecular support to the morphological characterization of metacestodes recorded in Octopus maya.

Scaevola rialagartensis (Goodeniaceae), a new species from coastal sand dunes of Rio Lagartos, Yucatan, Mexico

The new species, Scaevola rialagartensis Cast.-Campos is described and illustrated from coastal shrubland and vegetation bordering mangroves in Rio Lagartos, Yucatan, southeastern Mexico, where it is considered endemic. The new species is similar to S. plumieri, S. taccada and S. wrightii, all of which grow in similar environments, but can be differentiated from these in the size of shrubs, shape of axes, and nerves along leaves.

Factores ambientales relacionados con la cobertura de Agave angustifolia (Asparagaceae) en el matorral costero de Yucatán, México

Antecedentes y Objetivos: Agave angustifolia, o chelem, es el único maguey silvestre de la Península de Yucatán y es el ancestro de especies domesticadas de gran valor económico y cultural. Presta importantes servicios ambientales como recurso alimenticio para la fauna, fijación de suelos arenosos y captura de carbono en ambientes áridos con suelos pobres. Es un cultivo potencial de cara al aumento de las sequías predichas para la región y del empobrecimiento genético del henequén. El objetivo de este trabajo es recabar datos sobre la densidad de sus poblaciones, su patrón espacial, estructura poblacional y la relación entre su abundancia y los factores ambientales en el matorral costero de Yucatán, con el fin de evaluar su uso en la restauración ecológica.Métodos: Se muestrearon tres localidades costeras: Chuburná (Ch), San Benito (SB) y Río Lagartos (RL). En SB y RL se trazaron 36 cuadrantes de 4 m2; dentro de cada uno se estimó el porcentaje de cobertura de Agave angustifolia, el de los arbustos de más de 1 m de alto y la cobertura de mantillo. Se tomaron muestras de suelo a las que se analizó pH, conductividad eléctrica, nitrógeno total, materia orgánica e escala de gris. Se describieron la densidad poblacional, distribución espacial y estructura por tamaños de A. angustifolia en SB y Ch.Resultados clave: La cobertura de Agave angustifolia se correlaciona negativamente con la cobertura de arbustos y mantillo, y cantidad de materia orgánica. Las densidades de su población fueron inferiores a 0.1 individuos/m2, hubo una mayor proporción de plántulas y su distribución espacial es agregada.Conclusiones: Al soportar suelos pobres, altas temperaturas y radiación solar, la especie puede servir para restaurar algunas funciones ecológicas en las zonas más áridas de la costa donde la vegetación ha sido severamente dañada.

Integrating local knowledge for climate change adaptation in Yucatán, Mexico

Abstract The importance of local knowledge and traditional practices is now recognized by disaster risk reduction specialists, particularly in the aftermath of the tsunami in the Indian Ocean in 2004. However, these frequently used practices by local populations are not yet recognized by all actors involved in disaster prevention. This research seeks to identify local traditional practices which are connected to hydro-meteorological phenomena and climate change in the coastal areas of the Yucatan Peninsula in the Rio Lagartos Biosphere Reserve. The identification process requires observation, documentation, validation and categorization of local traditional knowledge. The traditional practices (mainly by fishermen as well as some farmers) examined specifically among the coastal populations relate to their habitat, natural resources, and fishing practices. Recognizing and valuing traditional knowledge will help improve resilience to the impact of disasters and the effects of climate change among coastal populations.

Presence of giant tiger shrimp Penaeus monodon (Fabricius, 1798) in eastern Peninsula of Yucatan coast, Mexico

Giant tiger shrimp Penaeus monodon has been indicated as an invader on the western coast of Atlantic Ocean. We report the first record of P. monodon in the eastern Peninsula of Yucatan, Mexico. On October 14 and November 25, 2014, three giant tiger shrimps were caught in Rio Lagartos lagoon. The total lengths of the shrimp were between 210 and 290 mm and weighed between 111.6 and 200 gr. Further sampling and monitoring is required in other coastal lagoons in Yucatan state to assess the invasion area and the origin as well as the probable invasion route of this species.

Acceso a la educación en salud y su potencial en la disminución de la incidencia de diarrea infantil en las poblaciones costeras de Yucatán, México

Introducción: La educación en salud o pláticas en el ámbito institucional mitiga la incidencia de diarrea infantil. Yucatán es el estado con las mayores tasas de incidencia de diarreas a nivel nacional; el impacto de las pláticas, como parte de un programa de salud, en la incidencia de diarreas ha sido insuficientemente estudiado. Objetivo: Analizar el rol del acceso a las pláticas para prevenir la incidencia de diarreas infantiles. Metodología: Se utilizó el muestreo de encuestas en 151 hogares, se encontró a 187 niños menores de cinco años de edad. El estudio se realizó en tres segmentos muestrales de la zona costera, con diferentes condiciones ambientales: Progreso (puerto urbano concentrado), Celestún (reserva biosfera, turismo, urbanizada) y Río Lagartos (turismo, reserva biosfera rural). Se estimó la tasa de prevalencia lápsica de diarrea, los casos fueron las diarreas ocurridas en los 15 días inmediatos previos a la encuesta. Se hizo análisis descriptivos, bivariados, estratificados y la regresión logística binaria. Resultados: Se registró una tasa de prevalencia lápsica de 13.37% (n=25 casos). El análisis logístico multivariado mostró el impacto protector significativo de las pláticas (=-2.105; RM=0.163; y = 0.018) con un efecto que equivale a 6.25 veces menos riesgo de presentar episodios diarreicos. Conclusión: Las pláticas, como política de salud, tienen impacto en la disminución de las diarreas; esto sucede en especial si se llevan a cabo entre los beneficiarios de los programas sociales.

Estructura genetica del copepodo Acartia lilljeborgii en la costa del estado de Yucatan, Mexico

We determined the genetic population structure and its implications within the food chain of the copepod Acartia lilljeborgii on the coast of Yucatan, by using isozymes and subsequent determination by electrophoresis. Nine systems were expressed up to 30-loci. Polymorphism and heterozygosity of the populations studied, when compared with other species of copepods were found to be low. The ST2 and PGM1 loci were expressed in all sampling sites. PGM1 showed the highest heterozygosity value (0.4728) and GPI1, with a value of 0.3200 was the lowest value. No system departed from the condition of the Hardy- Weinberg equilibrium. FST values were between values of -0.0798 to 0.5899 and the PGM1 for FBP1. The three populations of A. lilljeborgii analyzed in the coast of Yucatan, had low variability and genetic differentiation among populations, as indicated by the genetic distance values of 0.0585 which was the largest for the populations of Chelem and Rio Lagartos, suggesting that these populations are partially isolated. However, since A. lilljeborgii diapausic or resting eggs, which can be transported in or out of these bodies of water, it is likely that this condition holds allelic and genotypic frequencies similar or very close together. The results showed the existence of gene flow, given through a passive dispersal of diapausic eggs produced by this specie.

First reports of green turtles Chelonia mydas with fibropapillomas, in Yucatán, México

Fibropapillomas are cutaneous tumors that affect the health of marine turtles worldwide. In July 11th of 1998, a juvenile green turtle (Chelonia mydas) with tumors was captured by fishermen in the Sea Turtles Sanctuary of Rio Lagartos, Yucatán. The straight carapace length of this turtle was 44.6 cm, and we found 30 tumors with a size from 1 cm - 10 cm on the back flippers, neck, front flippers and in both eyes. On July 10th, 1999, another juvenile green turtle with fibropapillomatosis was captured by fishermen in the same area. This turtle was smaller (S.C.L. = 40.8 cm) with 5 small tumors (1 cm - 4 cm) on the back flippers and tail. The prevalence of fibropapillomatosis in Yucatan is low (2.4%). Considering the migratory route of this species and the high prevalence of green turtles with fibropapillomas in Florida, USA, we suggest an initial contagion between the populations ofthese peninsulas. Those are the first documented reports of green turtles with fibropapillomas in Yucatán, México.

Spatial characterization of a foraging area for immature hawksbill turtles (Eretmochelys imbricata) in Yucatan, Mexico

Abstract The submarine habitats in the Rio Lagartos Sea Turtle Sanctuary, Mexico, are an important feeding and development area for juvenile Hawksbill turtles (Eretmochelys imbricata). The characterization of these critical habitats is an important and urgent issue to attend for the conservation of this species in Mexico. The objective of this study is to identify, locate and describe the marine benthic habitats in this area, and explain the distribution of the juvenile Hawksbill turtles in the study area. We used submarine techniques such as videotransects and spot checks to characterize the bottom types in the area, and geostatistic techniques to elaborate thematic maps of the different benthic components, integrating all of them into a GIS. We obtained the bottom type map with eight submarine habitats at different depth ranges. We found juvenile Hawksbill turtles distributed mainly on hard bottom sites covered by octocorals, such as Pseudopterogorgia, and sponges of the genera Chondrilla and Spheciospongia. We estimated habitat ranges for the captured turtles and the bottom types occupied by them, then we calculated the distribution densities of juvenile Hawksbill turtles by bottom type. We concluded that the combination of spatial techniques and multivariate statistics is efficient for mapping the marine bottom types in the area, and recommend the generation of specific conservation strategies to protect this area because of the natural marine resources and process ocurring in it.

Epibionts of juvenile hawksbill turtle Eretmochelys imbricata in the Sanctuary of Sea Turtles of Rio Lagartos, Yucatan, México.

Studies about the relationship between sea turtles and epibionts are important for their conservation, because it gives us information about the effects of the epibionts on the turtles. During July and August of 1999, we counted the epibionts attached to each corporal region of 37 juvenile hawksbill turtle (Eretmochelys imbricata) captured in the Sanctuary of Sea Turtles of Rio Lagartos, Yucatán, México. The average size of the turtles was 36.4 (± 7.4) cm straight length. Barnacles presented the highest relative abundance: Platylepas sp. (97.2%), attached mainly to the neck and fins; Chelonibia testudinaria represented 1.6% attached only on the carapace and plastron. Leeches (Ozobranchus margoi) were found in the plastron and cloaca of two sea turtles; 43 mussels were registered under the scutes of the shell of one turtle. Filamentous algae were present in 20 turtles, mainly on the carapace. Oysters, amphipods, remoras, algae and percebes were scarcely registered. In general, the organisms associated to immature hawksbillturtles were commensals, although high amounts of epibionts could affect the energy cost of the sea turtleswhen they are swimming. In some cases the relation turned out to be parasitic, when the epibionts createdpossible sites of infections.

Fish community structure and dynamics in a coastal hypersaline lagoon: Rio Lagartos, Yucatan, Mexico

Rio Lagartos, a tropical coastal lagoon in northern Yucatan Peninsula of Mexico, is characterized by high salinity during most of the year (55 psu annual average). Even though the area has been designated as a wetland of international importance because of its great biodiversity, fish species composition and distribution are unknown. To determine whether the salinity gradient was influencing fish assemblages or not, fish populations were sampled seasonally by seine and trawl from 1992 to 1993 and bimonthly during 1997. We identified 81 fish species, eight of which accounted for 53.1% considering the Importance Value Index ( Floridichthys polyommus, Sphoeroides testudineus, Eucinostomus argenteus, Eucinostomus gula, Fundulus majalis, Strongylura notata, Cyprinodon artifrons and Elops saurus). Species richness and density declined from the mouth to the inner zone where extreme salinity conditions are prominent (>80) and competitive interactions decreased. However, in Coloradas basin (53 average sanity) and in the inlet of the lagoon, the highest fish density and number of species were observed. Greater habitat heterogeneity and fish immigration were considered as the best explanation. Multivariate analysis found three zones distinguished by fish occurrence, abundance and distribution. Ichthyofaunal spatial differences were attributed to selective recruitment from the Gulf of Mexico due to salinity gradient and to changing climatic periods. Estuarine and euryhaline marine species are abundant, with estuarine dependent ones entering the system according to environmental preferences. This knowledge will contribute to the management of the Special Biosphere Reserve through baseline data to evaluate environmental and anthropogenic changes.

Parasites and Symbionts of Native and Cultured Shrimps from Yucatán, Mexico

The prevalence of parasites and symbionts in various penaeid shrimps, including the native wild Farfantepenaeus aztecus (brown shrimp), F. duorarum (pink shrimp), and F. brasiliensis (pinkspotted shrimp) and the nonnative cultured Litopenaeus vannamei (Pacific white shrimp), along with those in the native wild Palaemonetes pugio (daggerblade grass shrimp), are reported. The native wild shrimp were collected from five sites on the coast of the Yucatán Peninsula of Mexico, namely, Celestun, Sisal, Chuburna, Dzilam, and Rio Lagartos. The most prevalent parasites and symbionts were the ciliates Apiosoma sp. (prevalence, 6–57%), Epistylis sp. (2–29%), and Zoothamnium penaei (2–65%), which were found in at least four of the five sites. Cultured shrimp from a shrimp farm at Sisal were found to be infected by Apiosoma sp. (6%), Epistylis sp. (2%), and the microsporidian Agmasoma penaei (also known as Thelohania penaei; 2%), presumably acquired from wild shrimp. Larvae of the cestode Prochristianella penaei had a prevalence ranging from 35% at Rio Lagartos to 100% at Celestun and Dzilam. The mean (±SD) abundance of P. penaei was between 2 ± 2 per shrimp for Rio Lagartos and 15 ± 17 for Chuburna. This parasite was recovered in shrimp from four sites. Histological examination of F. duorarum from Celestun revealed that P. penaei larvae (prevalence, 82%) were producing fibrosis in the hepatopancreas. The presence of the epibionts Z. penaei (64%) and Epistylis sp. (100%) did not produce histological damage in cultured L. vannamei from Sisal, nor did Lagenophrys eupagurus in P. pugio (100%) from Sisal. Seasonal sampling of shrimp for parasites and symbionts would help to clarify the possible pathological consequences of infection.

Culture of the American oyster, Crassostrea virginica (Gmelin 1971) in Rio Lagartos, Yucatan, Mexico

This research was done with the purpose to ascertain the biological feasibility of the culture of Crassostrea virginica (Gmelin 1971) at Rio Lagartos lagoon in Yucatán, México. Spat from two localities of the Golfo de México were grown in Nestier boxes: spat from Tamiahua, Veracruz, which had an initial average height of 22.50 ± 5.10 (SD) mm and initial total wet weight of 2.90 ± 1.64 g and spat from Mecoacán, Tabasco, that were 32.05 ± 4.50 mm and 5.53 ± 0.03 g, respectively. Both groups of oysters reached commercial size after 10 months of culture. Veracruz spat reached 65.00 ± 6.80 mm in height and 33.26 ± 7.02 g in total wet weight. Those from Tabasco reached 62.90 ± 6.70 mm in height and 33.97 ± 9.95 g in total wet weight. The mean physiological condition index for oysters from Tabasco was 5.96% and from Veracruz was 4.52%. Total survival rate was 63% for spat from Veracruz and 55% from Tabasco. Environmental conditions in the culture area proved to be favourable for the rearing of C. virginica.

Philometra margolisi n.sp. (Nematoda: Philometridae) from the gonads of the red grouper, Epinephelus morio (Pisces: Serranidae), in Mexico

A new nematode species, Philometra margolisi n.sp., is described from the gonads of the serranid fish Epinephelus morio from Mexico (localities Telchac, Chuburna, Progreso, and Rio Lagartos, Yucatan). It is characterized mainly by long (0.432–0.468 mm) and slender spicules and a simple gubernaculum (length 0.084–0.093 mm) in the male and by body shape and size (length 65–85 mm), arrangement and number of small cephalic papillae (eight papillae in an outer circle and four in an inner one), structure and length (1.07–1.18 mm) of the esophagus, long ovaries, and the presence of a pair of small lateral papilla-like projections on the elongate caudal end in gravid females.

Distribución de Ecteinascidia<i> turbinata</i> (Asddiacea: Pemphoridae) en los manglares de la Península de Yucatán, México

La ascidia Ecteinascidia turbinata sintetiza un grupo de moléculas consideradas hoy en día como unas de las más prometedoras contra diversos tipos de tumores. Sin embargo, la síntesis de este compuesto todavía no se ha podido conseguir químicamente, y la única fuente de producto activo la constituye las poblaciones naturales de este tunicado, el cual se cultiva o colecta en distintas partes del mundo para la obtención del producto activo. Con este trabajo, se ha intentado hacer una valoración preliminar de la población de E. turbinata en el Golfo de México y Península de Yucatán. Se muestrearon 33 localidades, desde el Estado de Veracruz en el Golfo de México, hasta Quintana Roo en el Caribe. Parece que la especie está bien establecida en la Península de Yucatán; sobre.itodo en el Mar Caribe, aunque se trata de poblaciones discontinuas y separadas geográficamente. Entre todas las localidades prospectadas, solo en Río Lagartos situada al Norte de la Península de Yucatán, se detectaron poblaciones con densidades próximas a 1 colonia/metro margen de manglar, y una producción media de 115 g de biomasa por metro lineal de manglar, que podría ofrecer posibilidades para establecer un programa de manejo del recurso de manera sustentable.